1. Field of the Invention
The present invention relates to a self-contained power source mounted in a pacing lead for generating electrical power for operating a pacing lead. The pacing lead is of the type designed to be implanted in a living organism, such as within a human's heart, such that movement of the heart acting on the pacing lead will cause generation of electrical power.
2. Description of the Prior Art
Heretofore various methods have been employed for generating electrical energy for electronic implants. In the Ko U.S. Pat. No. 3,456,134 there is disclosed an encapsulated cantilevered beam composed of a piezoelectric crystal mounted in a metal, glass or plastic container and arranged such that the cantilevered beam will swing in response to movement. The cantilevered beam is further designed to resonate at a suitable frequency and thereby generate electrical voltage.
In the Dahl U.S. Pat. No. 4,140,132 there is disclosed a piezoelectric crystal mounted in cantilevered fashion within an artificial pacemaker can or case, having a weight on one end, and arranged to vibrate to generate pulses which are a function of physical activity.
In the McLean U.S. Pat. No. 3,563,245 there is disclosed a pressure actuated electrical energy generating unit. A pressurized gas containing bulb is inserted into the heart whereby the contractions of the heart exert pressure on the bulb and cause the pressure within the bulb to operate a bellows remotely positioned with respect to the heart. This bellows in turn operates an electrical-mechanical transducer.
Further it has been proposed in the Frasier U.S. Pat. No. 3,421,512 to provide a pacer with a biological power supply which generates electrical power for the pacer utilizing a body fluid as an electrolyte.
It has also been suggested in the Enger U.S. Pat. No. 3,659,615 to use a piezoelectric bimorph encapsulated and implanted adjacent to the left ventricle of the heart and arranged to flex in reaction to muscular movement to generate electrical power.
Heretofore mounting of an power generation device in a catheter or tubing has not been proposed. However, the mounting of a sensor in a catheter has been proposed. For example, in the Shipley U.S. Pat. No. 2,967,865, strain gauges are used in a spiral configuration around a catheter to sense and transmit information regarding heart contractions.
Also, the use of piezoelectric material in the form of foils or bands wrapped around a patient's chest or leg has been experimentally suggested for measuring heart beats and blood flow. See for example "Ferroelectric Polymers and their Application" by Michael A. Marcus, appearing in "Ferroelectrics": 40 1982, and "Piezoelectric High Polymer Foils as Physiological Mechanic-Electric Energy Converters" by E. Hausler, H. Lang and F. J. Schreiner, appearing in "IEEE 1980 Biomedical Group Annual Conference, Frontiers of Engineering in Health Care".